arch/blackfin/kernel/ftrace.c

   1 /*
   2  * ftrace graph code
   3  *
   4  * Copyright (C) 2009 Analog Devices Inc.
   5  * Licensed under the GPL-2 or later.
   6  */
   7
   8 #include <linux/ftrace.h>
   9 #include <linux/kernel.h>
  10 #include <linux/sched.h>
  11 #include <asm/atomic.h>
  12
  13 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
  14
  15 /*
  16  * Hook the return address and push it in the stack of return addrs
  17  * in current thread info.
  18  */
  19 void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
  20                            unsigned long frame_pointer)
  21 {
  22         struct ftrace_graph_ent trace;
  23         unsigned long return_hooker = (unsigned long)&return_to_handler;
  24
  25         if (unlikely(atomic_read(&current->tracing_graph_pause)))
  26                 return;
  27
  28         if (ftrace_push_return_trace(*parent, self_addr, &trace.depth,
  29                                      frame_pointer) == -EBUSY)
  30                 return;
  31
  32         trace.func = self_addr;
  33
  34         /* Only trace if the calling function expects to */
  35         if (!ftrace_graph_entry(&trace)) {
  36                 current->curr_ret_stack--;
  37                 return;
  38         }
  39
  40         /* all is well in the world !  hijack RETS ... */
  41         *parent = return_hooker;
  42 }
  43
  44 #endif